This invention relates generally to robots for manipulating semiconductor wafers, flat panel displays, hard drive magnetic storage disks, printed circuitboards or other objects. More particularly, this invention relates to robots which handle wafers and position them accurately using an X-Y stage. The present invention employs an X-Y stage having an effector mounted on the X-Y stage.
Robots are commonly used in integrated circuit manufacturing to manipulate and position semiconductor wafers. Manipulation is necessary, for example, when wafers are inspected, tested or processed at a robotic station. Wafers arrive at the station stacked in cassettes, and a robot removes the wafers from the cassette one at a time for testing. In many testing procedures, the wafers are placed on an X-Y stage by the robot. The X-Y stage accurately positions the wafer with respect to an inspection/testing apparatus which performs measurements at precisely defined points on the wafer.
Examples of inspection/testing procedures include thin film quality and thickness measurements, stress measurements, or other measurements. Often, the measurements are optical.
At a robotic station, several cassettes are often used. For example, there may be a cassette for incoming wafers, a cassette for outgoing wafers, and a cassette for flawed wafers. The robot must be able to move wafers among all the cassettes as well as the X-Y stage. For this, the robot must have several degrees of freedom. Typically, the robot is capable of Z-motion, rotational motion (sometimes about two axes-one fixed, one movable), and linear motion. U.S. Pat. Nos. 4,695,215 and 5,105,147 show relevant examples of robots capable of moving wafers between several cassettes and a testing apparatus.
A problem with many prior art robotic testing stations is that the robots used are expensive and relatively large. It is important for all manufacturing equipment to be as small as possible because cleanroom space in a wafer fab is expensive. It would be an advance in the art of integrated circuit manufacturing equipment to provide a wafer handling apparatus that has a reduced size and cost.
Accordingly, it is a primary object of the present invention to provide a wafer handling apparatus that:
1) has a reduced size compared to prior art wafer handling and positioning devices;
2) has a reduced cost compared to prior art wafer handling and positioning devices;
3) is compatible with many different types of testing and processing stations.
These and other objects and advantages will be apparent upon reading the following description and accompanying drawings.
These objects and advantages are attained by an apparatus for handling and positioning a flat object delivered in a cassette. The cassette holds the object in the XY plane. The apparatus has a mounting means for mounting the cassette, an XY stage having an X-drive, a Y-drive, and a bed. The apparatus also has an effector and a chuck. The X-drive and Y-drive can move the bed in the X and Y directions, respectively. The effector is attached to the bed and can rotate about a Z-axis with respect to the bed. The chuck is attached to the bed. The chuck and effector are located such that the effector can place a flat object onto the chuck. The XY stage is located with respect to the mounting means such that the X-Y stage can cause the effector to pull the flat object from the cassette.
The apparatus may also have a second effector attached to the bed, with the second effector being rotatable with respect to the bed. The effectors can also be movable in the Z-direction. In a particular embodiment, the effectors can move in the Z direction between two discrete Z positions.
Preferably, the chuck is a vacuum chuck. The effector may also have holes for engaging the flat object with vacuum. Also, the chuck may be movable in the Z-direction. Preferably, the chuck has a recessed region for receiving the effector when the effector places a flat object on the chuck.
The present invention also includes an XY stage having an X-drive, a Y-drive, a bed, an effector and a chuck. The bed is attached to the X-drive and Y-drive so that the bed is movable by the X and Y drives. The effector is attached to the bed and is capable of rotation about a Z-axis with respect to the bed. The chuck is also attached to the bed and is disposed such that the effector can place flat objects onto the chuck, and remove objects from the chuck.
The XY stage may also include a second effector. Also, the chuck may have a recessed region for accommodating the effector.
Alternatively, the effector can move linearly with respect to the bed. In this embodiment, the effector is not rotatable.